This application claims the priority of German application 197 21 614.5, filed in Germany on May 23, 1997, the disclosure of which is (are) expressly incorporated by reference herein.
The present invention relates to a press arrangement having at least two press stations, particularly a multistation press, sliding tables arranged in the press stations for receiving molds as required, the sliding tables being movable out of the respective press station, a transfer system which is used for the workpiece transport and which has workpiece holders, which can be separated from the transfer system, for the temporary holding of workpieces, at least one intermediate depositing device which is arranged between two press stations and which is provided with workpiece depositing apparatus as well as with a receiving device for the workpiece holders.
The present invention also relates to a method for tool exchange on a press arrangement having at least two press stations, particularly on multistation presses, sliding tables, which can be moved out of the press stations and on which molds are held, during the process, workpiece holders of a transfer system used for the workpiece transport being transferred to an intermediate depositing device which, in addition to workpiece receiving devices, has corresponding devices for receiving the workpiece holders, and relate also to a use of an intermediate depositing device pertaining to a press arrangement having at least two press stations, sliding tables arranged in the press stations for receiving molds as required, the sliding tables, being movable out of the respective press station, a transfer system which is used for the workpiece transport and which has workpiece holders which can be separated from the transfer system for the temporary holding of workpieces, and at least one intermediate depositing device which is arranged between two press stations and which is provided with devices for depositing workpieces as well as with a receiving device for the workpiece holders.
As a rule, presses or press arrangements have workpiece-dependent components which are to be exchanged, as required, for example, when the production is changed. First, these components are molds whose bottom mold part is held on a sliding table and whose top mold part is held on a press slide. The sliding table can usually be moved out in the lateral direction of the press or the press arrangement. In addition, the workpiece-dependent components comprise parts of the transfer system which is used for the conveying of the workpieces from press station to press station. The transfer system frequently has holding devices (e.g., vacuum suction devices) whose position and number is workpiece-determined.
The vacuum suction devices are usually held on suction frames which, in turn, are held on cross traverses of a two-axis transfer. The suction frames are workpiece-specific. Additional workpiece-specific elements are found on intermediate depositing devices which are arranged between two press stations and temporarily receive the workpieces without any machining being carried out on them. For receiving the workpieces, the intermediate depositing devices have depositing means called "templates" whose shape, size and position are dependent on the respective workpiece to be deposited. The holding means and the templates form the so-called tooling.
The change of all components, that is, of the mold, of the holding means and of the depositing means is to take place as automatically as possible and/or at low manual expenditures.
EP-A-0 191 397 describes a transfer press having intermediate depositing devices is known whose templates are transferred before the mold exchange to corresponding holding systems of the sliding table or of the mold disposed on this sliding table. For the transfer, the intermediate depositing device has a separate transfer device which is formed by a toothed rack and by a spring mechanism for guiding the template on a straight path to the sliding table. Devices for changing workpiece-specific elements of the transfer device are, however, not shown.
DE 41 24 083 A1 shows a transfer press line in which intermediate depositing devices are arranged between individual press stations and are moved laterally out of the press line during the mold exchange. The intermediate depositing devices hold the depositing templates used for receiving the workpieces so that they can be swivelled about a transverse axis. In addition, holding systems are provided at the intermediate depositing devices for receiving suction devices which are part of the transfer device. During the mold exchange, the intermediate devices, together with the depositing templates and the suction devices, are moved laterally out of the press. For this purpose, a corresponding clearance must be provided in the area of the press stands.
DE 33 34 021 C1 discloses a large-piece transfer press having an intermediate depositing device which has a gripping and holding device for depositing templates. For the mold exchange, these templates can be connected with the mold. For transporting the depositing templates from the intermediate depositing device to the molds, the gripping and holding device is used which, for this purpose, has toothed racks which are disposed to be slidable in the transport direction and are correspondingly driven and on whose outer end the templates are held. The exchange of workpiece-specific elements of the transfer system is not, however, taken into account in this case.
An object of the present invention is to provide a press arrangement which permits a mold and tool exchange at low manual expenditures.
Another object to provide a method for carrying out a mold and tool exchange.
These objects are achieved by a press arrangement in which at least one sliding table carries at least one holding device for the workpiece holders separated from the transfer system, and the intermediate depositing device has at least one transfer device for receiving and transferring the workpiece holders from the transfer system to the holding device.
The method of the present invention also achieves these objects by receiving the workpiece holders from the transfer system by way of the intermediate depositing device and transferring them to at least one holding device which is carried by the sliding table or the mold, and by using the intermediate depositing device for transferring the workpiece holders to a holding device provided on at least one of the sliding tables.
In addition to the sliding tables, which are in any event present and which carry molds which can be exchanged as required, the press arrangement according to the invention has a transfer system with workpiece-specific workpiece holding apparatus (suction frames) and intermediate depositing devices with also workpiece-specific workpiece depositing apparatus (templates). In addition, the intermediate depositing devices have transfer devices which are set up for taking over the workpiece holding apparatus of the transfer system and for transferring them to corresponding holding devices which are provided on the sliding tables and/or molds.
As a result, the intermediate depositing device can be used during the mold exchange as a handling device for transferring the workpiece holding apparatus from the transfer system to the sliding tables. The intermediate depositing device will then deposit the workpiece depositing apparatus and the workpiece holding apparatus simultaneously or successively on the holding device of the sliding table or of the mold resting thereon.
This arrangement and approach permit in particular the deposition of the workpiece holding apparatus at a point on the sliding table or the mold which cannot be reached by the transfer system itself. For example, the holding device for the workpiece holding apparatus may be arranged at a very low level. The intermediate depositing device bridges the distance between the transfer system and the holding device. Consequently, the tooling, i.e., the workpiece depositing apparatus and the workpiece holding apparatus, can be arranged at a low level. This benefits the mold exchange during which the mold is, for example, by way of a crane, lifted off the sliding table and another mold is placed on the sliding table.
As required, the holding device may also be provided on the mold which can then be stored with the pertaining tooling. Assignment problems between workpiece holding apparatus, workpiece depositing apparatus and molds are almost impossible. This approach simplifies the storage to great advantage.
Preferably, only the specifically constructed workpiece holding apparatus of the transfer system is exchanged. This means that, for example, carrying rails and cross traverses remain in the press arrangement and suction frames carried by the cross traverses are exchanged. The cross traverses remaining in the transfer system results in a noticeable saving of cost. For reducing weight, the cross traverses are often produced from carbon fiber materials so that every other, otherwise required set of cross traverses would clearly have cost disadvantages. Because of the fixedly mounted cross traverses and as the result of the weight reduction, there is an improvement of the dynamics and a reduction of the required driving energy.
High-expenditure and weight-intensive coupling devices for connecting the cross traverses are unnecessary. Separate holders for the workpiece depositing apparatus and the workpiece holding apparatus can be provided on the mold or on the sliding table as well as a holding arrangement which carries the workpiece depositing apparatus and, as required, receives the workpiece holding apparatus, whereby the holding arrangement is fastened on the mold-side or sliding-table-side holder.
The above arrangement is particularly advantageous if at least one supporting tube extending through in the transverse direction is part of the holding arrangement, on which supporting tube the workpiece depositing apparatus, such as the templates, are held. The supporting tubes may have individual holding elements for receiving the workpiece holding apparatus. The supporting tubes bridge the machine width in the transverse direction so that several workpiece holding apparatuses can be disposed on a supporting tube arrangement which, in turn, is again disposed on the holders of the sliding table or of the mold. The supporting tube arrangement is preferably fixedly connected with the templates and therefore forms the support thereof and thus forms an intermediate holding system for the holding apparatus. This intermediate holding system bridges, for example, a waste shaft adjoining the sliding table.
The intermediate depositing device is preferably disposed on a support so that it can be swivelled about a transverse axis. The support is also disposed on a lifting head so that it can also be swivelled about a transverse axis. The lifting head is preferably held so that it can be adjusted in at least two axes, preferably in three axes. By way of the swivelling of the support, different swivelling positions of the workpiece situated on the template can be adjusted. The swivelling of the templates has the purpose of changing these templates from their working position into a passive or depositing position. Thereby, the templates are movable via the sliding tables between the stands of one of the presses. While the transfer device, for example, a pin connected with the supporting tube, in the normal operative position of the templates, points to the lifting head and is therefore essentially horizontally aligned, it will stand up vertically when the templates swivel into the passive position. In this position, the pin will be ready to receive the holding apparatus.
Staying spaces are assigned to the holding apparatus and the depositing apparatus (templates) which, in the transfer direction, are arranged in front of and behind the mold or the sliding table and which mutually overlap with respect to the transverse direction. This permits a space-saving housing of the tooling while the accessibility to the mold is simultaneously good.
Other objects, advantages and novel features of the present invention will become apparent from the following detailed description of the invention when considered in conjunction with the accompanying drawings.